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Thanks to all who replied to
the request for Bandwidth information.
After the recent ROS
EME and 500/1 500/8 data tests , I have been in
conversation with Jose over the bandwidth constrictions
part of the MF permits , as we are 'all' aware there are
other contentions expressed elsewhere , however , I think in response
to the tests conducted via this reflector, and a series
of emails over the possibility of a faster
version of the eme narrow mode, Jose has indicted
that he will prepare a narrow data mode , similar
to the existing ros systems , but with a bandwidth
of 100 Hz and a enhanced data rate to a 'qso' mode
to quote :-
''I think i have the solution. I could do a mode of 100 HZ at 6.25 baud.
Speed it would be about 150 characters/minute, half of PSK31, and 8.5dB better
than PSK31.''
I hope this mode will be useful to
the holders of permits allocating 100 Hz , we have already the
comments from JIm and Andy over the issues of the
legality of the system , so hopefully once the
bandwidth constriction's are met , this my pave the way
for data operations on 500 and possibly 137 ? , as
the system will be single carrier, phase continuous thus
may be amplified by class e/d amplifiers and will be resistant
to phase distortion , which from the previous
ZL2AFP sounder tests ( http://groups.google.com/group/uk500khz/web/zl2afp-psk-sounder )
explains the poor performance of psk on 500.
Tnx Graham
G0NBD
Sent: Thursday, May 06, 2010 2:08 PM
Subject: Re: LF: 500 Permit emission’s bandwidth? EU and Global
??
Thank you , Rik,
From that , its possible that the
other permits are similar
Ok Tnx - G .
Sent: Thursday, May 06, 2010 1:19 PM
Subject: RE: LF: 500 Permit emission’s bandwidth? EU and Global
??
Graham,
the document that gives us access to 500kHz says
100Hz bandwidth, but does not say how many dB's the signal has to be attenuated
at these limits.
73, Rik ON7YD - OR7T
Ok Many thanks' for the
reply's
From that .... next is :-
From the data, I assume that
100 Hz is the common limiting factor for a narrow
band data transmission that could be used by all who
'wanted' to use it ?..(noted on the cw keying
speed ~ BW)
So if a value of 100 Hz is
specified, what is the 'presumed' roll-off of the power in the
said bands ?, assuming that the original concept was
based on CW operation , which by definition 'has to' generate
sidebands , there must be an assumed tolerance ?
Q would the deployment of a
system that could defined as 125 hz bandwidth
ie 100 Hz with +/- 12.5 Hz overspill , cause
a technical breach of the regulations or
be viewed as occupying the 'allocated' bandwidth
for a telegraphy transmission ? ,
Taking that spectral measurements in
the 10 Hz region are perhaps starting
to test even the best equipment, the area is
perhaps a little empiric ?
I use the word telegraphy, purposely to
view/observe the situation interims of the licence
conditions and not on the basis of 'mode' which
like Liverpool and Everton have there own sub cultures
but are still football teams ..
Thanks
Graham
G0NBD
Sent: Wednesday, May 05, 2010 10:39 PM
Subject: LF: 500 Permit emission’s bandwidth? EU and Global
??
500 Permit
emission’s bandwidth?
Can any one
indicated what is the permitted
‘telegraphy’ bandwidth
of the various ‘new’ 500KHz licences
or special permits issued round
the EU and now the rest of the
Globe ?
I have the
impression that 100 Hz is the maximum ‘telegraphy’ transmission bandwidth, in
some cases, eg , Belgium at 100
Hz . Others appear to be some what wider or not defined ?.
Norway is CW only ? what is the Dutch
allocation ? Southern Ireland ? ... etc
Are
Beacons defined by mode or
bandwidth ?
Tnx –
Graham
G0NBD
(I use
the word ‘telegraphy’ as defined by
the ITU R V.662-3 , please no
reference to key clicks !
)
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